Method of making hot metals with totally recycled gas

Abstract

A method is provided to improve the production of hot direct reduced iron in a melter-gasifier; reduction furnace system. All of the reduction gas produced in the melter gasifier and the top gas produced in reduction furnace which has been stripped of CO 2 are recycled to the reduction furnace. The reduction furnace is sized to process all this gas and bypassed direct reduced iron may result.

What is claimed is: 
     
       1. A method of making molten iron utilizing a direct reduction furnace and a melter gasifier comprising providing a melter gasifier which is capable of forming a reduction gas during reaction of coke, oxygen and direct reduced iron; providing a direct reduction furnace which is capable of forming a top gas containing CO 2  during reduction of iron ore, said direct reduction furnace having sufficient capacity to utilize all of the reduction gas produced by the melter gasifier and the top gas produced by said direct reduction furnace after the CO 2  has been removed therefrom for the direct reduction of iron ore; introducing carbonaceous fuel into the melter gasifier; blowing oxygen containing gas into said melter gasifier and combusting said carbonaceous fuel to form at least a first fluidized bed of coke particles from said carbonaceous fuel; reducing iron ore in said reduction furnace to direct reduced iron; producing a top gas in said reduction furnace; flowing said top gas out of said reduction furnace and removing CO 2  from said top gas to form a recycle gas containing all of said top gas remaining after CO 2  removal; introducing at least a portion of said direct reduced iron into said melter gasifier through an entry port in the upper portion thereof; reacting coke, oxygen and direct reduced iron in said melter gas out of combust the major portion of said coke to produce reduction gas, molten iron and a processed slag; flowing reduction gas out of said melter gasifier; combining all of said reduction gas with all of said recycle gas from said reduction furnace to form a combined gas; directing all of the combined gas to said reduction furnace; reacting said combined reduction gas with iron ore in said reduction furnace to convert the iron ore to direct reduced iron; discharging a portion of the direct reduced iron directly to the melter gasifier for further processing and bypassing a portion of the direct reduced iron coming from said reduction furnace from the melter gasifier for other uses. 
     
     
       2. The method of claim 1 further characterized in that the carbonaceous fuel is petroleum coke. 
     
     
       3. The method of claim 1 further characterized in that the carbonaceous fuel is coal. 
     
     
       4. The method of claim 1 wherein the carbonaceous fuel is a mixture of petroleum coke and coal. 
     
     
       5. The method of claim 1 where the recycle gas is preheated prior to being combined with the reduction gas. 
     
     
       6. The method of claim 5 where the recycle gas is preheated to at least 500° C. 
     
     
       7. The method of claim 5 where the recycle gas is preheated to about 600° C. 
     
     
       8. The method of claim 5 where the portions of the direct reduced iron discharged to the melter gasifier and the portion of the direct reduced iron bypassed form the melter gasifier are about equal.